U.S. patent application number 16/921748 was filed with the patent office on 2020-10-22 for asymmetrically shaped light-emitting device, backlight module using the same, and method for manufacturing the same.
This patent application is currently assigned to Maven Optronics Co., Ltd.. The applicant listed for this patent is Maven Optronics Co., Ltd.. Invention is credited to Chia-Hsien CHANG, Chieh CHEN.
Application Number | 20200335678 16/921748 |
Document ID | / |
Family ID | 1000004939762 |
Filed Date | 2020-10-22 |
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United States Patent
Application |
20200335678 |
Kind Code |
A1 |
CHEN; Chieh ; et
al. |
October 22, 2020 |
ASYMMETRICALLY SHAPED LIGHT-EMITTING DEVICE, BACKLIGHT MODULE USING
THE SAME, AND METHOD FOR MANUFACTURING THE SAME
Abstract
An asymmetrically shaped chip-scale packaging (CSP)
light-emitting device (LED) includes an LED chip, a
photoluminescent structure (or a light-transmitting structure), and
a reflective structure. The photoluminescent structure covers the
upper surface and/or the edge surface of the LED chip; and the
reflective structure at least partially covers the edge surface of
the photoluminescent structure. The reflective structure partially
reflects the primary light emitted from the edge surface of the LED
chip or the converted secondary light radiated from the edge
surface of the photoluminescent structure, therefore shaping the
radiation pattern asymmetrically.
Inventors: |
CHEN; Chieh; (Palo Alto,
CA) ; CHANG; Chia-Hsien; (New Taipei City,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Maven Optronics Co., Ltd. |
Hsinchu County |
|
TW |
|
|
Assignee: |
Maven Optronics Co., Ltd.
Hsinchu County
TW
|
Family ID: |
1000004939762 |
Appl. No.: |
16/921748 |
Filed: |
July 6, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16040492 |
Jul 19, 2018 |
10749086 |
|
|
16921748 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 33/508 20130101;
H01L 2933/0058 20130101; H01L 33/58 20130101; H01L 33/54 20130101;
H01L 33/10 20130101; H01L 33/46 20130101; H01L 33/36 20130101; G02F
1/133603 20130101; H01L 2933/0025 20130101; H01L 33/60
20130101 |
International
Class: |
H01L 33/60 20060101
H01L033/60; G02F 1/13357 20060101 G02F001/13357; H01L 33/10
20060101 H01L033/10; H01L 33/36 20060101 H01L033/36; H01L 33/58
20060101 H01L033/58; H01L 33/46 20060101 H01L033/46 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 21, 2017 |
CN |
201710601827.1 |
Jul 21, 2017 |
TW |
106124542 |
Claims
1. A light-emitting device comprising: a light-emitting chip
comprising an upper surface, a lower surface opposite to the upper
surface, an edge surface and a set of electrodes, wherein the edge
surface extends between the upper surface and the lower surface,
the set of electrodes is disposed on the lower surface, and the set
of electrodes and the lower surface form a lower electrode surface;
an optical structure comprising a top surface, a bottom surface
opposite to the top surface, and a side surface, wherein the side
surface extends between the top surface and the bottom surface, and
the optical structure covers the upper surface of the
light-emitting chip, the edge surface of the light-emitting chip,
or both, wherein the optical structure is a photoluminescent
structure or a light-transmitting structure; and a reflective
structure partially covering the side surface of the optical
structure; wherein: a first horizontal direction and a second
horizontal direction perpendicular to each other are specified
along a length direction and a width direction on the upper surface
of the light-emitting chip, respectively; and the side surface of
the optical structure comprises four vertical side surfaces;
wherein: two vertical side surfaces of the four vertical side
surfaces are oppositely disposed substantially perpendicular to the
first horizontal direction; and another two vertical side surfaces
of the four vertical side surfaces are oppositely disposed
substantially perpendicular to the second horizontal direction;
wherein: one of the vertical side surfaces substantially
perpendicular to the second horizontal direction is covered by the
reflective structure to form a side reflective surface; another of
the vertical side surfaces substantially perpendicular to the
second horizontal direction is not covered by the reflective
structure to form a side light-emitting surface; and the side
light-emitting surface of the light-emitting device and the lower
electrode surface of the light-emitting chip are substantially
perpendicular to each other; wherein a distance between the side
reflective surface and the edge surface of the light-emitting chip
along the second horizontal direction is smaller than a distance
between the side light-emitting surface and the edge surface of the
light-emitting chip along the second horizontal direction.
2. The light-emitting device of claim 1, wherein: the upper surface
and the edge surface of the light-emitting chip are both covered by
the optical structure; the top surface of the optical structure and
the two vertical side surfaces of the optical structure disposed
oppositely to each other and substantially perpendicular to the
first horizontal direction are not covered by the reflective
structure to form a top light-emitting surface and two side
light-emitting surfaces; the top light-emitting surface of the
light-emitting device and the lower electrode surface of the
light-emitting chip are substantially parallel to each other; and
the two side light-emitting surfaces of the light-emitting device
and the lower electrode surface of the light-emitting chip are
substantially perpendicular to each other.
3. The light-emitting device of claim 1, wherein: the upper surface
and the edge surface of the light-emitting chip are both covered by
the optical structure; the top surface of the optical structure is
covered by the reflective structure to form an upper reflective
surface; the two vertical side surfaces of the optical structure
disposed oppositely to each other and substantially perpendicular
to the first horizontal direction are not covered by the reflective
structure to form two side light-emitting surfaces; and the two
side light-emitting surfaces of the light-emitting device and the
lower electrode surface of the light-emitting chip are
substantially perpendicular to each other.
4. The light-emitting device of claim 1, wherein: the edge surface
of the light-emitting chip is covered by the optical structure; the
upper surface of the light-emitting chip and the top surface of the
optical structure are both covered by the reflective structure to
form an upper reflective surface; the two vertical side surfaces of
the optical structure disposed oppositely to each other and
substantially perpendicular to the first horizontal direction are
not covered by the reflective structure to form two side
light-emitting surfaces; and the two side light-emitting surfaces
of the light-emitting device and the lower electrode surface of the
light-emitting chip are substantially perpendicular to each
other.
5. The light-emitting device of claim 1, wherein: the upper surface
and the edge surface of the light-emitting chip are both covered by
the optical structure; the top surface of the optical structure is
covered by the reflective structure to form an upper reflective
surface; and the two vertical side surfaces of the optical
structure disposed oppositely to each other and substantially
perpendicular to the first horizontal direction are covered by the
reflective structure to form two side reflective surfaces.
6. The light-emitting device of claim 1, wherein: the edge surface
of the light-emitting chip is covered by the optical structure; the
upper surface of the light-emitting chip and the top surface of the
optical structure are both covered by the reflective structure to
form an upper reflective surface; and the two vertical side
surfaces of the optical structure disposed oppositely to each other
and substantially perpendicular to the first horizontal direction
are both covered by the reflective structure to form two side
reflective surfaces.
7. The light-emitting device of any one of claims 2 to 6, wherein
the optical structure further comprises a micro-structured lens
layer.
8. The light-emitting device according to any one of claims 2 to 6,
further comprising a submount substrate, wherein the light-emitting
device is electrically connected with the submount substrate.
9. The light-emitting device of any one of claims 2 to 6, wherein
the optical structure further comprises at least one
light-transmitting layer.
10. The light-emitting device of any one of claims 2 to 6, wherein
the reflective structure comprises a light-transmitting resin
material, and optical scattering particles dispersed in the
light-transmitting resin material.
11. The light-emitting device of claim 10, wherein: the
light-transmitting resin material comprises polyphthalamide,
polycyclohexylene-dimethylene terephthalate, epoxy molding
compound, or silicone; and the optical scattering particles
comprise titanium dioxide, boron nitride, silicon dioxide, or
aluminum oxide.
12. A backlight module comprising: an application mounting board
comprising a horizontal surface; the light-emitting device of claim
1 disposed on the application mounting board; a reflective layer
disposed above the horizontal surface of the application mounting
board; and a light guide plate disposed above the reflective layer;
wherein the light guide plate comprises an incident-light side
surface and an exiting-light surface connected to the
incident-light side surface and facing away from the reflective
layer.
13. The backlight module of claim 12, wherein: the application
mounting board further comprises a vertical surface; the
light-emitting device is disposed on the vertical surface of the
application mounting board; the side light-emitting surface of the
light-emitting device faces the horizontal surface of the
application mounting board; a top light-emitting surface of the
light-emitting device faces toward the incident-light side surface
of the light guide plate.
14. The backlight module of claim 13, wherein: a length of the top
light-emitting surface of the light-emitting device is specified
along the second horizontal direction; a thickness of the light
guide plate is specified along a normal direction of the
exiting-light surface; and the length of the top light-emitting
surface is not greater than the thickness of the light guide
plate.
15. The backlight module of claim 13, wherein the application
mounting board further comprises a reflective layer that covers the
vertical surface, the horizontal surface, or both.
16. The backlight module of claim 13, wherein the application
mounting board is a flexible application mounting board.
17. The backlight module of claim 12, wherein: the light-emitting
device is disposed on the horizontal surface of the application
mounting board; and the side light-emitting surface of the
light-emitting device faces toward the incident-light side surface
of the light guide plate.
18. The backlight module of claim 17, wherein: a length of the side
light-emitting surface of the light-emitting device is specified
along a normal direction of the upper surface of the light-emitting
chip; a thickness of the light guide plate is specified along a
normal direction of the exiting-light surface; and the length of
the side light-emitting surface is not greater than the thickness
of the light guide plate.
19. The backlight module of claim 17, wherein the application
mounting board further comprises a reflective layer covering the
horizontal surface.
20. A method of manufacturing a light-emitting device, comprising:
disposing an optical structure to cover an upper surface of a
light-emitting chip, an edge surface of the light-emitting chip, or
both; and forming a reflective structure to partially cover a side
surface of the optical structure; wherein: a first horizontal
direction and a second horizontal direction are specified along a
length direction and a width direction on the upper surface of the
light-emitting chip, respectively; and the side surface of the
optical structure comprises four vertical side surfaces; wherein:
two vertical side surfaces of the four vertical side surfaces are
oppositely disposed substantially perpendicular to the first
horizontal direction; and another two vertical side surfaces of the
four vertical side surfaces are oppositely disposed substantially
perpendicular to the second horizontal direction; wherein: one of
the vertical side surfaces substantially perpendicular to the
second horizontal direction is covered by the reflective structure
to form a side reflective surface; and another of the vertical side
surfaces substantially perpendicular to the second horizontal
direction is not covered by the reflective structure to form a side
light-emitting surface; wherein a distance between the side
reflective surface and the edge surface of a light-emitting chip
along the second horizontal direction is smaller than a distance
between the side light-emitting surface and the edge surface of a
light-emitting chip along the second horizontal direction.
21. The method of claim 20, wherein, in disposing the optical
structure, the method further comprises: forming the optical
structure on the upper surface and the edge surface of the
light-emitting chip; and cutting the optical structure along the
first horizontal direction to form a first trench and exposing the
side surface of the optical structure to be covered by the
reflective structure; wherein, in forming the reflective structure,
the reflective structure is formed to fill the first trench.
22. The method of claim 21, wherein, in forming the reflective
structure, the reflective structure further covers a top surface of
the optical structure.
23. The method of claim 22, wherein the method further comprises:
cutting the optical structure along the second horizontal direction
to form a second trench and exposing the two vertical side surfaces
substantially perpendicular to the first horizontal direction; and
wherein, in forming the reflective structure, the reflective
structure is formed to fill the second trench.
24. The method of claim 20, wherein, in disposing the optical
structure, the method further comprises: forming the optical
structure to cover the edge surface of the light-emitting chip; and
cutting the optical structure along the first horizontal direction
to form a first trench, and exposing the side surface to be covered
by the reflective structure; wherein, in forming the reflective
structure, the reflective structure is formed to fill the first
trench, and furthermore to cover a top surface of the optical
structure and the upper surface of the light-emitting chip.
25. The method of claim 24, wherein forming the reflective
structure further comprises: cutting the optical structure along
the second horizontal direction to form a second trench and
exposing the two vertical side surfaces substantially perpendicular
to the first horizontal direction; and wherein the reflective
structure is formed to fill the second trench.
26. The method of claim 20, further comprising: cutting the optical
structure along the first horizontal direction and then followed by
cutting the optical structure along the second horizontal
direction.
27. The method of claim 20, further comprising cutting the optical
structure, and cutting the reflective structure, where cutting the
reflective structure is concurrent with cutting the optical
structure.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 16/040,492, filed Jul. 19, 2018, which application claims
the benefit of and priority to Taiwan Patent Application No.
106124542 filed on Jul. 21, 2017, and Chinese Patent Application
No. 201710601827.1 filed on Jul. 21, 2017, the disclosures of which
are incorporated herein by reference in their entirety.
BACKGROUND
Technical Field
[0002] The present disclosure relates to a light-emitting device
and a method of manufacturing the same; and more particularly
relates to an asymmetrically shaped chip-scale packaging (CSP)
light-emitting device (LED) used in a Liquid Crystal Display (LCD)
backlight module, and a method of manufacturing the same.
Description of the Related Art
[0003] An LED chip is generally used as a light source for
illumination, backlight, or an indicator lamp inside electronic
products. Specifically, an LED chip generating a primary light is
usually placed inside a package structure to form an LED package,
wherein photoluminescent materials are typically dispensed to cover
the radiation path of the LED chip so that a portion of the primary
light is converted as secondary light by the photoluminescent
materials. Reflective materials are also used as a part of the
package structure so that desirable light-emitting directions can
be achieved.
[0004] Among them, a Plastic Leaded Chip Carrier (PLCC) LED package
can be categorized as a top-view LED package or a side-view LED
package according to their light-emitting direction. A top-view LED
package is used as a light source for general lighting or a
backlight source for direct-lit LCD displays, whereas a side-view
LED package is used as a backlight source for edge-lit LCD displays
for televisions or mobile devices. Either a top-view LED package or
a side-view LED package has a primary light-emitting surface. An
optical axis of an LED package is generally specified by an axis
passing through the center of the primary light-emitting surface
(for example, a rectangle) and perpendicular to the primary
light-emitting surface. For the sake of simplicity, two additional
axes are specified to be along the length and the width directions
of the primary light-emitting surface, and both are perpendicular
to the optical axis, wherein the axis along the length direction
and that along the width direction are also perpendicular to each
other. When the radiation pattern is measured along the length
direction and the width direction of a top-view LED package (or a
side-view LED package), the same (or similar) radiation pattern can
usually be obtained. Because the top-view LED package or side-view
LED package has the same or similar radiation patterns along the
length and width directions, the PLCC-type LED package has a
symmetrical radiation pattern.
[0005] This type of LED packages with a symmetrical radiation
pattern cannot satisfy some applications specifying an asymmetrical
radiation pattern, such as street lighting. Another application
specifies the light source of the backlight module for the edge-lit
type LCD for televisions or mobile devices to have an asymmetrical
radiation pattern, where a larger angle of radiation pattern along
the length direction of the LED packages (or the length direction
of the backlight module) is desirable. In this way, a radiation
pattern with a large viewing angle along the length direction can
provide a more uniform incident light distribution to the light
guide plate, thus reducing dark spots or areas along the light
guide plate. The number of LED packages used in a light bar along
the light guide plate can also be reduced as well if a light source
having a large viewing angle is used. An edge-lit light source also
should provide a smaller viewing angle of the radiation pattern
along the width direction of the LED package (or the thickness
direction of the backlight module) so that the incident light can
be effectively transmitted from the LED light source to the light
guide plate of the backlight module instead of leaking out of the
light guide plate, thereby increasing light utilization
efficiency.
[0006] For a PLCC-type LED package, whether it is top-view or
side-view, it uses a lead frame with a reflective cup as its main
design structure. Furthermore, it is usually packaged with an LED
chip dispensed with a photoluminescent material. Specifically, the
PLCC reflective cup is usually fabricated by molding. If a
PLCC-type LED package is used in applications specifying an
asymmetrical radiation pattern, an extra optical lens or secondary
optical lens is incorporated to shape the light to achieve a
specified radiation pattern, which inevitably will increase the
manufacturing cost. Also, the overall space used to achieve an
asymmetrical radiation pattern is greatly increased, which is not
favorable to the design of an end product of consumer electronics
nowadays. If an optical lens is not used to shape the radiation
pattern, an alternative approach is that a portion of the
reflective cup structure of the lead frame is fabricated to be
light-transmitting. That is, the light can penetrate through this
portion of the light-transmitting structure so that the radiation
pattern can be changed. However, the reflective cup structure of
the lead frame is usually fabricated through molding. Therefore,
the LED package having an asymmetrically shaped geometry, such as a
reflective cup with a partial light-transmitting structure and a
partial reflective structure, is difficult to fabricate using a
mass production process. Therefore, a streamlined and cost
effective method to achieve an asymmetrical radiation pattern for a
PLCC type LED package remains desired.
[0007] As the size of LCDs for televisions and mobile devices
continue to move toward thinner in form factors and lighter in
weight, the PLCC-type LED package used as a backlight source also
has to be continuously reduced in size. In this trend, a CSP LED
with a small form factor has been developed recently. CSP LEDs have
become one of the main development trends in the LED industry. For
example, CSP LEDs have been introduced to replace the top-view PLCC
LEDs used in direct-lit backlight LCD TVs. The application of CSP
LEDs in backlight can further reduce the size of the LED backlight
module, and simultaneously obtain higher light intensity. The
smaller size of a CSP LED is advantageous in the design of a
secondary optical lens, and the higher light intensity is
beneficial to the design of a brighter LCD or otherwise to the
reduction of the number of the LEDs used.
[0008] According to the number of the light emission surfaces, CSP
LEDs can be categorized into two types: top-surface emitting and
five-surface emitting. As for a top-surface emitting CSP LED, four
vertical edge surfaces of the flip-chip LED chip are covered with a
reflective material so that the light is radiated solely or
primarily from the top surface of the CSP LED. Therefore a
top-surface emitting CSP LED has a smaller viewing angle (about
120). The light of a five-surface emitting CSP LED can be
transmitted outwardly from the top surface as well as the four
vertical edge surfaces of the CSP LED, which therefore has a larger
viewing angle (about 140.degree..about.160). However, similar to
the PLCC-type LED packages, both of the two types of CSP LEDs
belong to the category of light-emitting devices having a
symmetrical radiation pattern, and therefore both types of CSP LEDs
cannot satisfy the application specifying an asymmetrical radiation
pattern. In addition, for a CSP LED, if a primary optical lens or a
secondary optical lens is used to generate an asymmetrical
radiation pattern, not only the production cost is significantly
increased, but also the space of the CSP LED together with the lens
is greatly increased, which will defeat the advantage of a small
form factor of the CSP LED. Therefore, an effective design is still
lacking to achieve an asymmetrical radiation pattern while using a
CSP LED.
[0009] For a side-view PLCC package or other side-view surface
mount LED packages, even though the primary light-emitting surface
of a side-view package is perpendicular to the bonding pad surface
of the package, the primary light-emitting surface is still
substantially in parallel with the electrode surface of the LED
chip. As for a CSP LED, a lead frame or a submount substrate is
usually not included. That is, the electrode surface of a CSP LED
is in parallel and in contact with the application mounting board.
Therefore, in some embodiments of this disclosure, a top-view CSP
will be specified with the technical feature that the primary
light-emitting surface and the electrode surface of a CSP LED are
substantially in parallel; whereas a side-view CSP will be
specified with the technical feature that the primary
light-emitting surface and the electrode surface of a CSP LED are
substantially perpendicular.
[0010] Therefore, although the CSP LED can be greatly reduced in
size, the CSP LEDs used in backlight applications are top-view CSP
LEDs. That is, the primary light-emitting surface and the lower
electrode surface of a CSP LED are substantially parallel to each
other. When a top-view CSP LED is used as a backlight source in an
edge-lit LCD, a special L-shaped light bar design is included so
that the primary light-emitting surface of the CSP LED faces the
incident-light side of the light guide plate. The L-shaped light
bar will increase production cost and the difficulty of alignment
between the light bar and the light guide plate. Also, the increase
of thickness of the light bar module in the normal direction of the
light-emitting surface causes a larger display frame bezel size. If
the primary light-emitting surface and the lower electrode surface
of a CSP LED are perpendicular to each other, it is specified as a
side-view CSP LED. When a CSP LED with a side-view structure is
adopted, an L-shaped light bar may be omitted to turn the top
light-emitting surface 90 degrees toward the incident-light side of
the light guide plate. Accordingly, the thickness of the light bar
module along the direction of the light-emitting surface can be
effectively reduced.
[0011] Therefore, it remains desired to fabricate a small
form-factor CSP LED with an asymmetrical geometric structure to
achieve an asymmetrical radiation pattern in a low-cost and
efficient manner; and to realize a small form-factor side-view CSP
LED with the primary light-emitting surface and the lower electrode
surface perpendicular to each other, which can be applied to the
edge-lit type backlight module to reduce the thickness of the light
bar module along the direction of the light-emitting surface so as
to further reduce the display frame bezel size.
SUMMARY
[0012] An object of some embodiments of the present disclosure is
to provide a top-view CSP LED having asymmetrically shaped
reflective surfaces, a backlight module including the top-view LED,
and a method for manufacturing the top-view LED, so that the
radiation angle of the LED is effectively restricted in certain
light-emitting directions to generate an asymmetrical radiation
pattern.
[0013] Another object of some embodiments of the present disclosure
is to provide a side-view CSP LED having a primary light-emitting
surface and a lower electrode surface substantially perpendicular
to each other, a backlight module including the side-view LED, and
a manufacturing method to fabricate the side-view LED
[0014] In order to achieve the above objects, a top-view LED having
an asymmetrically shaped reflective structure according to some
embodiments of the present disclosure includes: an LED chip, a
photoluminescent structure, and a reflective structure. The LED
chip has an upper surface, a lower surface opposite to the upper
surface, an edge surface and a set of electrodes. The edge surface
is formed and extends between the upper surface and the lower
surface, and the set of electrodes is disposed on or adjacent to
the lower surface to form a lower electrode surface. Furthermore, a
first horizontal direction and a second horizontal direction
perpendicular to each other are specified along the length
direction and the width direction on the upper surface of the LED
chip, respectively. The photoluminescent structure has a top
surface, a bottom surface opposite to the top surface, and a side
surface. The side surface is formed and extends between the top
surface and the bottom surface. The photoluminescent structure
covers the upper surface and/or the edge surface of the LED chip.
The reflective structure partially covers the side surface of the
photoluminescent structure. The side surface of the
photoluminescent structure has four vertical side surfaces. Two
vertical side surfaces of the four vertical side surfaces are
oppositely disposed perpendicular to the second horizontal
direction, wherein one of them is covered by the reflective
structure to form a side reflective surface, and the other is not
covered by the reflective structure to form a side light-emitting
surface, and the side light-emitting surface and the lower
electrode surface of the LED chip are substantially perpendicular
to each other. Another two vertical side surfaces are oppositely
disposed perpendicular the first horizontal direction to form two
side light-emitting surfaces.
[0015] In order to achieve the above object, some embodiments
according to the present disclosure are directed to a side-view CSP
LED, including: an LED chip, a photoluminescent structure, and a
reflective structure. The LED chip has an upper surface, a lower
surface opposite to the upper surface, an edge surface and a set of
electrodes. The edge surface is formed and extends between the
upper surface and the lower surface, and the set of electrodes is
disposed on or adjacent to the lower surface. The set of electrodes
and the lower surface collectively form a lower electrode surface
of the LED chip. Furthermore, a first horizontal direction and a
second horizontal direction perpendicular to each other are
specified along the length direction and the width direction on the
upper surface of the LED chip. The photoluminescent structure
covers the edge surface and/or the upper surface of the LED chip.
The reflective structure substantially completely covers the top
surface of the photoluminescent structure to form an upper
reflective surface, and partially covers the side surface of the
photoluminescent structure to form at least one side reflective
surface.
[0016] To achieve the above object, other embodiments of the
present disclosure are directed to a top-view monochromatic LED
having an asymmetrical reflective structure, including: an LED
chip, a light-transmitting structure, and a reflective structure,
wherein the LED chip has an upper surface, a lower surface opposite
to the upper surface, an edge surface and a set of electrodes. The
edge surface is formed and extends between the upper surface and
the lower surface, and the set of electrodes is disposed on or
adjacent to the lower surface. The set of electrodes and the lower
surface collectively form a lower electrode surface. Furthermore, a
first horizontal direction and a second horizontal direction
perpendicular to each other are specified along the length
direction and the width direction on the upper surface of the LED
chip, respectively. The light-transmitting structure has a top
surface, a bottom surface opposite to the top surface, and a side
surface. The side surface is formed and extends between the top
surface and the bottom surface. The light-transmitting structure
covers the upper surface of the LED chip and/or the edge surface.
The reflective structure partially covers the side surface of the
light-transmitting structure. The side surface of the
light-transmitting structure has four vertical side surfaces. Two
vertical side surfaces of the four vertical side surfaces are
oppositely disposed perpendicular to the second horizontal
direction; one of them is covered by the reflective structure to
form one side reflective surface; the other is not covered by the
reflective structure to form a side light-emitting surface; and the
side light-emitting surface and the lower electrode surface of the
LED chip are substantially perpendicular to each other. Another two
vertical side surfaces are oppositely disposed perpendicular to the
first horizontal direction and are not covered by the reflective
structure to form two side light-emitting surfaces.
[0017] In order to achieve the above object, other embodiments
according to the present disclosure are directed to a monochromatic
side-view CSP LED, including: an LED chip, a light-transmitting
structure, and a reflective structure. The LED chip has an upper
surface, a lower surface opposite to the upper surface, an edge
surface and a set of electrodes. The edge surface is formed and
extends between the upper surface and the lower surface, and the
set of electrodes is disposed on or adjacent to the lower surface
to form a lower electrode surface. Furthermore, a first horizontal
direction and a second horizontal direction perpendicular to each
other are specified along the length direction and the width
direction on the upper surface of the LED chip, respectively. The
light-transmitting structure covers the upper surface and/or the
edge surface of the LED chip. The reflective structure
substantially completely covers the top surface of the
light-transmitting structure to form an upper reflective surface,
and partially covers the side surface of the light-transmitting
structure to form at least one side reflective surface.
[0018] To achieve the above object, a backlight module according to
some embodiments of the present disclosure includes an application
mounting board, a plurality of the top-view or side-view LEDs
according to embodiments of the present disclosure, a reflective
layer, and a light guide plate. The application mounting board
includes a horizontal surface and/or a vertical surface. A
plurality of the LEDs is disposed on the application mounting board
to form a light bar. The reflective layer is disposed above the
horizontal surface of the application mounting board. The light
guide plate is disposed above the reflective layer, including an
incident-light side surface and an exiting-light surface that is
connected to the incident-light side surface and faces away from
the reflective layer.
[0019] To achieve the above object, a method of manufacturing a
top-view or a side-view LED disclosed according to some embodiments
of the present disclosure includes: disposing a photoluminescent
structure or a light-transmitting structure to cover an upper
surface and/or an edge surface of an LED chip; and forming a
reflective structure to partially cover one vertical side surface
of the photoluminescent structure or the light-transmitting
structure. A first horizontal direction and a second horizontal
direction perpendicular to each other are specified along the
length direction and the width direction on the upper surface of
the LED chip, respectively. The side surface of the
photoluminescent structure or the light-transmitting structure has
four vertical side surfaces. Two vertical side surfaces of the four
vertical side surfaces are disposed oppositely to each other
perpendicular to the second horizontal direction, wherein one of
them is covered by the reflective structure to form a side
reflective surface, while the other is not covered by the
reflective structure to form a side light-emitting surface. Another
two vertical side surfaces of the four vertical side surfaces are
oppositely disposed perpendicular to the first horizontal
direction.
[0020] In this arrangement, the photoluminescent structure covers
the upper surface and/or the edge surface of the LED chip, and the
reflective structure partially covers the side surface of the
photoluminescent structure to partially reflect the light emitted
from the edge surface of the LED chip and/or the light emitted from
the side surface of the photoluminescent structure. Therefore, an
asymmetrical radiation pattern with respect to the normal direction
of the light-emitting surface along the first horizontal direction
and/or along the second horizontal direction can be formed.
Furthermore, the reflective structure can substantially completely
cover the upper surface, and partially cover the edge surface of
the LED chip to form a side-view CSP LED with a technical feature
that a primary light-emitting surface and a lower electrode surface
are substantially perpendicular to each other. Therefore, the LED
can provide properly specified asymmetrical radiation patterns in
different applications without the aid of an additional optical
lens, thereby effectively reducing the manufacturing cost of the
LED, while retaining the advantage of its small size to facilitate
a compact design of the end product.
[0021] Furthermore, the top-view or side-view LED can provide a
larger viewing angle along the length direction of the light guide
plate, so that dark areas can be minimized or the distance between
two adjacent LEDs can be increased (the number of LEDs used in a
light bar can be reduced). Meanwhile, the LED can provide a smaller
viewing angle along the thickness direction of the light guide
plate, so that the light emitted by the LED can be more effectively
transmitted to the light guide plate, thereby reducing the loss of
light energy. Moreover, the primary light-emitting surface of the
LED may further be specified to be substantially perpendicular to
the lower electrode surface of the LED to form a side-view CSP LED.
When the side-view LED is applied to an edge-lit backlight module,
an L-shape application mounting board of the light bar designed for
using a top-view LED may be omitted. Instead, a horizontal
application mounting board of the light bar for using a side-view
LED is sufficient. Elimination of the vertical portion of the
L-shape application mounting board reduces the overall thickness of
the light bar and the difficulty of alignment and manufacturing.
Therefore, the display using this side-view LED backlight module
can have a narrower frame bezel.
[0022] Other aspects and embodiments of the disclosure are also
contemplated. The foregoing summary and the following detailed
description are not meant to restrict the disclosure to any
particular embodiment but are merely meant to describe some
embodiments of the disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1A, FIG. 1B, FIG. 1C, FIG. 1D, and FIG. 1E are two
perspective views and three cross-sectional views of a top-view LED
according to one embodiment of the present disclosure.
[0024] FIG. 2A, FIG. 2B, FIG. 2C, and FIG. 2D are two perspective
views and two cross-sectional views of a top-view LED according to
another embodiment of the present disclosure.
[0025] FIG. 3A, FIG. 3B, FIG. 3C, and FIG. 3D are two perspective
views and two cross-sectional views of a side-view LED according to
another embodiment of the present disclosure.
[0026] FIG. 3E and FIG. 3F are two cross-sectional views of a
side-view LED according to another embodiment of the present
disclosure.
[0027] FIG. 4A, FIG. 4B, FIG. 4C, and FIG. 4D are two perspective
views and two cross-sectional views of a side-view LED according to
another embodiment of the present disclosure.
[0028] FIG. 4E and FIG. 4F are cross-sectional views of a side-view
LED according to another embodiment of the present disclosure.
[0029] FIG. 5 is a schematic diagram of a backlight module
including a top-view LED according to an embodiment of the present
disclosure.
[0030] FIG. 6 is a schematic view of a backlight module including a
side-view LED according to an embodiment of the present
disclosure.
[0031] FIG. 7A and FIG. 7B illustrate a top view schematic diagram
and a side view schematic diagram of the backlight module shown in
FIG. 5 and FIG. 6, respectively.
[0032] FIG. 8A, FIG. 8B, FIG. 9A, FIG. 9B, FIG. 9C, FIG. 10A, FIG.
10B, FIG. 11A, FIG. 11B, FIG. 12A, and FIG. 12B are schematic
diagrams of process stages of a manufacturing method to fabricate a
top-view LED according to one embodiment of the present
disclosure.
[0033] FIG. 13A, FIG. 13B, FIG. 14A, FIG. 14B, FIG. 14C, FIG. 15A,
FIG. 15B, FIG. 16A, FIG. 16B, FIG. 17A, and FIG. 17B are schematic
diagrams of process stages of a manufacturing method to fabricate a
top-view LED according to another embodiment of the present
disclosure.
[0034] FIG. 18A, FIG. 18B, FIG. 19A, FIG. 19B, FIG. 19C, FIG. 20A,
FIG. 20B, FIG. 21A, FIG. 21B, FIG. 22A, and FIG. 22B are schematic
diagrams of process stages of a manufacturing method to fabricate a
side-view LED according to another embodiment of the present
disclosure.
[0035] FIG. 23A, FIG. 23B, and FIG. 23C are schematic diagrams of
process stages of a partial manufacturing method to fabricate a
top-view or a side-view LED according to another embodiment of the
present disclosure.
DETAILED DESCRIPTION
Definitions
[0036] The following definitions apply to some of the technical
aspects described with respect to some embodiments of the
disclosure. These definitions may likewise be expanded upon
herein.
[0037] As used herein, the singular terms "a," "an," and "the" may
include plural referents unless the context clearly dictates
otherwise. Thus, for example, reference to a layer can include
multiple layers unless the context clearly dictates otherwise.
[0038] As used herein, the term "set" refers to a collection of one
or more components. Thus, for example, a set of layers can include
a single layer or multiple layers. Components of a set also can be
referred to as members of the set. Components of a set can be the
same or different. In some instances, components of a set can share
one or more common characteristics.
[0039] As used herein, the term "adjacent" refers to being near or
adjoining. Adjacent components can be spaced apart from one another
or can be in actual or direct contact with one another. In some
instances, adjacent components can be connected to one another or
can be formed integrally with one another. In the description of
some embodiments, a component provided "on" or "on top of" another
component can encompass cases where the former component is
directly on (e.g., in direct physical contact with) the latter
component, as well as cases where one or more intervening
components are located between the former component and the latter
component. In the description of some embodiments, a component
provided "underneath" another component can encompass cases where
the former component is directly beneath (e.g., in direct physical
contact with) the latter component, as well as cases where one or
more intervening components are located between the former
component and the latter component.
[0040] As used herein, the terms "connect," "connected," and
"connection" refer to an operational coupling or linking. Connected
components can be directly coupled to one another or can be
indirectly coupled to one another, such as via another set of
components.
[0041] As used herein, the terms "about", "substantially", and
"substantial" refer to a considerable degree or extent. When used
in conjunction with an event or circumstance, the terms can refer
to instances in which the event or circumstance occurs precisely as
well as instances in which the event or circumstance occurs to a
close approximation, such as accounting for typical tolerance
levels of the manufacturing operations described herein. For
example, when used in conjunction with a numerical value, the terms
can encompass a range of variation of less than or equal to .+-.10%
of that numerical value, such as less than or equal to .+-.5%, less
than or equal to .+-.4%, less than or equal to .+-.3%, less than or
equal to .+-.2%, less than or equal to .+-.1%, less than or equal
to .+-.0.5%, less than or equal to .+-.0.1%, or less than or equal
to .+-.0.05%. For example, "substantially" transparent can refer to
a light transmittance of at least 70%, such as at least 75%, at
least 80%, at least 85% or at least 90%, over at least a portion or
over an entirety of the visible spectrum. For example,
"substantially" flush can refer to two surfaces within 20
micrometers of lying along a same plane, such as within 10
micrometer of lying along the same plane, or within 5 micrometer of
lying along the same plane. For example, "substantially" parallel
can refer to a range of angular variation relative to 0.degree.
that is less than or equal to .+-.10.degree., such as less than or
equal to .+-.5.degree., less than or equal to .+-.4.degree., less
than or equal to .+-.3.degree., less than or equal to
.+-.2.degree., less than or equal to .+-.1.degree., less than or
equal to .+-.0.5.degree., less than or equal to .+-.0.1.degree., or
less than or equal to .+-.0.05.degree.. For example,
"substantially" perpendicular can refer to a range of angular
variation relative to 90.degree. that is less than or equal to
.+-.10.degree., such as less than or equal to .+-.5.degree., less
than or equal to .+-.4.degree., less than or equal to
.+-.3.degree., less than or equal to .+-.2.degree., less than or
equal to .+-.1.degree., less than or equal to .+-.0.5.degree., less
than or equal to .+-.0.1.degree., or less than or equal to
.+-.0.05.degree..
[0042] As used herein with respect to photoluminescence, the term
"efficiency" or "quantum efficiency" refers to a ratio of the
number of output photons to the number of input photons.
[0043] As used herein, the term "size" refers to a characteristic
dimension. In the case of an object (e.g., a particle) that is
spherical, a size of the object can refer to a diameter of the
object. In the case of an object that is non-spherical, a size of
the non-spherical object can refer to a diameter of a corresponding
spherical object, where the corresponding spherical object exhibits
or has a particular set of derivable or measurable characteristics
that are substantially the same as those of the non-spherical
object. When referring to a set of objects as having a particular
size, it is contemplated that the objects can have a distribution
of sizes around that size. Thus, as used herein, a size of a set of
objects can refer to a typical size of a distribution of sizes,
such as an average size, a median size, or a peak size.
[0044] FIGS. 1A and 1B show two perspective views, and FIGS. 1C and
1D show two cross-sectional views of a top-view LED 1A according to
an embodiment of the present disclosure. The LED 1A includes an LED
chip 10, an optical structure 20, and a reflective structure 30.
The technical details of the components will be described below in
sequence.
[0045] The LED chip 10 is a flip-chip light-emitting semiconductor
chip, and has an upper surface 11, a lower surface 12, an edge
surface 13, and a set of electrodes 14, as illustrated in FIGS. 1C
and 1D. The upper surface 11 is disposed oppositely relative to the
lower surface 12, and the upper surface 11 and the lower surface 12
may be rectangular, and two side edges or lines of the rectangular
upper surfaces 11 (and the corresponding lower surface 12) are
substantially in parallel with a first horizontal direction D1 and
the other two side edges or lines are substantially in parallel
with a second horizontal direction D2. In other words, the first
horizontal direction D1 and the second horizontal direction D2 are
specified perpendicular to each other along the length direction
and the width direction on the upper surface 11 of the LED chip 10,
respectively. A thickness direction (direction perpendicular to the
upper surface 11, not shown) is specified to be along the vertical
direction perpendicular to both of the first horizontal direction
D1 and the second horizontal direction D2
[0046] The edge surface 13 is formed between the upper surface 11
and the lower surface 12, and extends and connects the periphery of
upper surface 11 and that of the lower surface 12. In other words,
the edge surface 13 is formed along the periphery edge of the upper
surface 11 and the periphery edge of the lower surface 12, so that
the edge surface 13 is annular (for example, a rectangular ring)
with respect to the upper surface 11 and the lower surface 12. The
edge surface 13 further includes four vertical edge surfaces 131a
to 131d (the edge surface 13 is divided into the four vertical edge
surfaces 131a to 131d), wherein the two vertical edge surfaces 131a
and 131c are oppositely disposed and are perpendicular to the first
horizontal direction D1, and the other two vertical edge surfaces
131b and 131d are oppositely disposed and are perpendicular to the
second horizontal direction D2.
[0047] The set of electrodes 14, having two or more electrodes, is
disposed on or adjacent to the lower surface 12. The set of
electrodes 14 and the lower surface 12 are collectively referred to
as a lower electrode surface hereinafter. The light-emitting active
layer of the LED chip 10 is located near the lower surface 12 of
the LED chip 10 and above the set of electrodes 14 (not shown). The
space defined between the active layer, the upper surface 11, and
four vertical edge surfaces 131a to 131d is formed of a transparent
substrate material (e.g., Sapphire). Electrical energy (not shown)
can be supplied to the LED chip 10 through the set of electrodes 14
to energize the active layer so that a primary light is radiated
through electroluminescence (converting the electrical energy to
optical energy) of the active layer. Since the LED chip 10 is of a
flip-chip type, no electrode is disposed on the upper surface 11,
and a light radiated by the active layer of the LED chip 10 can be
transmitted out of the LED chip 10 from the upper surface 11 as
well as the four vertical edge surfaces 131a to 131d of the edge
surface 13.
[0048] An example embodiment of the optical structure 20 is a
photoluminescent structure 20 to form a white LED. Another example
embodiment of the optical structure 20 is a substantially
transparent light-transmitting structure 20 to form a monochromatic
LED. Hereinafter, a photoluminescent structure 20 will firstly be
used as an embodiment to illustrate the technical features of the
LED 1A. The photoluminescent structure 20, which can be used to
convert portions of the primary light emitted by the LED chip 10 to
a secondary light with different wavelengths to form a light beam
L, includes a light-transmitting resin material and a
photoluminescent material, wherein the photoluminescent material
can be uniformly dispersed in the light-transmitting resin material
so that the photoluminescent structure 20 does not have a distinct
layered structure. The photoluminescent structure 20 may also
include a photoluminescent layer and a substantially transparent
light-transmitting layer (or light-transmitting structure) stacked
on each other. For specific technical details, reference may be
made to the U.S. patent application Ser. No. 15/416,921 (published
as US 2017/0222107) for a photoluminescent structure with a
light-transmitting layer stacked on a photoluminescent layer.
[0049] As illustrated in FIGS. 1A to 1D, the photoluminescent
structure 20 has a top surface 21, a bottom surface 22, and a side
surface 23, wherein the top surface 21 and the bottom surface 22
are disposed oppositely to each other, and the top surface 21 and
the bottom surface 22 may be rectangular. The two side edges or
lines of the top surface 21 are substantially in parallel with the
first horizontal direction D1, and the other two side edges or
lines are substantially in parallel with the second horizontal
direction D2. The bottom surface 22 of the photoluminescent
structure 20 and the lower surface 12 of the LED chip 10 together
form a lower surface of the LED 1A. The top surface 21 and the
bottom surface 22 are horizontal surfaces and may also be
substantially parallel to each other.
[0050] The side surface 23 is formed between the top surface 21 and
the bottom surface 22, and connects the periphery of top surface 21
and that of the bottom surface 22. In other words, the side surface
23 is formed along the periphery edge of the top surface 21 and the
bottom surface 22, so that the side surface 23 is annular (e.g., a
rectangular ring) along the top surface 21 and bottom surface 22.
The side surface 23 further includes four vertical side surfaces
231a to 231d (the side surface 23 is divided into the four vertical
side surfaces 231a to 231d), wherein the two vertical side surfaces
231a and 231c are oppositely disposed and are perpendicular to the
first horizontal direction D1, and the other two vertical side
surfaces 231b and 231d are oppositely disposed and are
perpendicular to the second horizontal direction D2.
[0051] In terms of the relative position, the photoluminescent
structure 20 is disposed on the LED chip 10 and substantially
completely covers (e.g., covers at least 90%, at least 95%, at
least 98%, or at least 99% or more of a total surface area) the
upper surface 11 and the edge surface 13 of the LED chip 10, so
that the top surface 21 of the photoluminescent structure 20 is
located above the upper surface 11 of the LED chip 10.
[0052] As shown in FIG. 1C, the reflective structure 30 can block
and reflect the light beam L so that the radiation angle of the
light beam L is constrained. In this embodiment, the reflective
structure 30 partially covers the side surface 23 and solely covers
one side of the side surface 23 of the photoluminescent structure
20 (also indirectly covers and shields one side of the edge surface
13 of the LED chip 10). Specifically, among the four vertical side
surfaces 231a to 231d of the side surface 23, one of the vertical
side surfaces 231a to 231d perpendicular to the second horizontal
direction D2, for example the vertical side surface 231b, is
directly shielded by the reflective structure 30 to form a side
reflector. The vertical edge surface 131b of the LED chip 10
together with the vertical side surface 231b of the
photoluminescent structure 20 are directly or indirectly covered by
the reflective structure 30. In other words, the other vertical
side surface 231d of the photoluminescent structure 20, the
vertical side surfaces 231a and 231c oppositely disposed
perpendicular to the first horizontal direction D1, and the top
surface 21 are not covered by the reflective structure 30. That is,
the vertical side surfaces 231a, 231c, and 231d not covered by the
reflective structure 30 form three side light-emitting surfaces,
and the top surface 21 that is not shielded by the reflective
structure 30 forms a top light-emitting surface. Therefore, the
light partially emitted by the LED chip 10 and partially converted
by the photoluminescent structure 20 traveling toward the vertical
side surface 231b will be reflected back (or absorbed) by the
reflective structure 30, and mix together to form the light beam L,
which can radiate out of the photoluminescent structure 20 from the
light-emitting surfaces, namely the vertical side surfaces 231a,
231c, and 231d and the top surface 21.
[0053] Desirably, the side light-emitting surfaces and the lower
electrode surface are substantially perpendicular to each other.
That is, the side light-emitting surfaces and the lower electrode
surface are designed to be fabricated to be perpendicular to each
other. Due to tolerances or variations of a manufacturing process
or other factors, the side light-emitting surface could be slightly
inclined with respect to the lower electrode surface as a result.
Under a slight inclination angle, the side light-emitting surface
and the lower electrode surface are still considered to be
substantially perpendicular to each other. Desirably, the top
light-emitting surface and the lower electrode surface are
substantially parallel to each other. That is, the top
light-emitting surface and the lower electrode surface are designed
to be fabricated to be parallel to each other. However, the top
light-emitting surface relative to the lower electrode may be
slightly inclined because of tolerance and variations of a
manufacturing process. Even under slight inclination, the top
light-emitting surface and the lower electrode surface are still
considered to be substantially parallel to each other.
[0054] Desirably, when the reflective structure 30 covers the side
surface 23, it adjoins the side surface 23 so that there is
substantially no gap between the reflective structure 30 and the
side surface 23. Therefore, the reflective structure 30 has an
inner side surface 33 adjoining and contacting the side surface 23
of the photoluminescent structure 20. The reflective structure 30
also has an outer side surface 34 opposite to the inner side
surface 33, which functions as a side reflective surface, and the
outer side surface 34 may be a vertical surface. Also, the top
surface 31 of the reflective structure 30 can be substantially
flush with the top surface 21 of the photoluminescent structure 20,
and a bottom surface of the reflective structure 30 can be
substantially flush with the bottom surface 22 of the
photoluminescent structure 20.
[0055] As for the manufacturing material, the reflective structure
30 may be formed of a material including a light-transmitting resin
material and optical scattering particles dispersed inside the
light-transmitting resin material. The light-transmitting resin
material may be, for example, polyphthalamide (PPA),
polycyclohexylene-dimethylene terephthalate (PCT), epoxy molding
compound (EMC), or silicone; and the optical scattering particles
can be, for example, titanium dioxide particles, boron nitride
particles, silicon dioxide particles, aluminum oxide particles, or
other ceramic particles.
[0056] In addition, the LED 1A may also include a submount
substrate 50 (see FIG. 1E). The submount substrate 50 may be a
ceramic substrate, a glass substrate, a silicon substrate, a
printed circuit board (PCB), a metal-core PCB, or the like. The
submount substrate 50 has wires (not shown) that can conduct
electric energy. When the LED 1A is electrically connected with the
submount substrate 50, electric power can be transmitted to the LED
1A through the submount substrate 50 to make it emit light. The LED
1A with a submount substrate 50 may facilitate the attachment
process; such as a surface mount process for module-level
applications. The submount substrate 50 may also be included in
other embodiments disclosed in the present disclosure.
[0057] The above is the technical content of each component of the
LED 1A, which has at least the following technical features.
[0058] As shown in FIG. 1C and FIG. 1D, after the primary light
generated from the LED chip 10 enters the photoluminescent
structure 20, the light beam L radiating toward the vertical side
surface 231b is reflected back by the reflective structure 30 and
mixed with another portion of the light together. Eventually, the
light beam L passes through the photoluminescent structures 20 and
escapes either from the side light-emitting surfaces (the vertical
side surfaces 231a, 231c, and 231d) or the top light-emitting
surface (the top surface 21). Therefore, the light beam L traveling
along the first horizontal direction D1 is not significantly
affected and constrained by the reflective structure 30, and
therefore has a larger viewing angle. On the other hand, the light
beam L traveling toward the vertical side surface 231b along the
second horizontal direction D2 will be reflected back by the
reflective structure 30. Because the light beam L is shielded by
the reflective structure 30 along the second horizontal direction
D2, the viewing angle is smaller than the former and is re-directed
toward certain specific directions (toward the vertical side
surface 231d that is not shielded by the reflective structure 30).
Therefore, an asymmetrical radiation pattern is formed along the
normal direction of the upper surface 11 of the LED chip 10 (for
example, the optical axis of the upper surface 11). In general, the
viewing angle of the light beam L emitted by the LED 1A along the
first horizontal direction D1 is larger, and the viewing angle
along the second horizontal direction D2 is smaller and the
radiation pattern is asymmetrical.
[0059] Desirably, the length of the top surface 21 along the first
horizontal direction D1 may be larger than the width of the top
surface 21 along the second horizontal direction D2, which is
beneficial to make the light beam L along the first horizontal
direction D1 having a larger viewing angle than the viewing angle
along the second horizontal direction D2.
[0060] In summary, the LED 1A may provide different viewing angles
along different horizontal directions D1 and D2, and form an
asymmetrical radiation pattern with respect to the normal direction
of the light-emitting surface along a specific horizontal direction
so as to provide non-symmetrical radiation patterns.
[0061] Another embodiment of the optical structure 20 of the LED 1A
is a substantially transparent light-transmitting structure 20 to
form a monochromatic LED 1A. That is, the LED 1A will include the
LED chip 10, a light-transmitting structure 20 (or a
light-transmitting layer), and the reflective structure 30.
Thereby, the wavelength of the light emitted by the LED chip 10 is
not converted when passing through the light-transmitting structure
20. The LED 1A with the light-transmitting structure 20 can be used
to generate monochromatic light such as red light, green light,
blue light, infrared light, or ultraviolet light with an
asymmetrical radiation pattern. The technical feature of this
embodiment of the monochromatic light CSP LED can also be applied
to other embodiments disclosed below.
[0062] In addition, the LED 1A may further include a
micro-structured lens layer 40 (see FIG. 1E). Desirably, the
micro-structured lens layer 40 can be simultaneously formed during
the manufacture of the optical structure 20 through molding or
other fabrication methods to integrally form the optical structure
20 and the micro-structured lens layer 40 together. The
micro-structured lens layer 40 may be composed of a plurality of
microstructures regularly arranged or randomly formed, and the
microstructures may be hemispherical, pyramidal, columnar, conical
or the like or may be rough surfaces. Thereby, the micro-structured
lens layer 40 can prevent the light transmitted out of the LED 1A
from being reflected back to the optical structure 20 due to total
internal reflection, thereby increasing the light extraction
efficiency and improving the luminous efficacy of the LED 1A. This
technical feature of an optical structure 20 having a
micro-structured lens layer can also be applied to other
embodiments disclosed in the present disclosure.
[0063] The above is a description of the technical features of the
LED 1A. Next, the technical features of LEDs according to other
embodiments of the present disclosure will be described, and the
technical features of other embodiments of the LEDs should be
cross-referenced to each other, so that the same or similar
technical features will be omitted or simplified for the sake of
brevity.
[0064] FIGS. 2A to 2B show two perspective views of an LED 2A, and
FIGS. 2C to 2D show two cross-sectional views of the LED 2A
according to another embodiment of the present disclosure, wherein,
for the purpose of illustration, a photoluminescent structure 20 is
used as an example embodiment of the optical structure 20. The LED
2A differs from the LED 1A at least in that the area of the bottom
surface 22 of the photoluminescent structure 20 is larger than the
area of the upper surface 11 of the LED chip 10 so that the upper
surface 11 of the LED chip 10 is completely covered by the
photoluminescent structure 20. Furthermore, the edge surface 13 of
the LED chip 10 is covered and surrounded by the reflective
structure 30. More specific details are as follows.
[0065] The area of the upper surface 11 of the LED chip 10 is
smaller than the area of the bottom surface 22 of the
photoluminescent structure 20 and is completely covered by the
photoluminescent structure 20. Also, the four vertical edge
surfaces 131a to 131d of the edge surface 13 of the LED chip 10 are
not covered by the photoluminescent structure 20 but are covered by
the reflective structure 30. The primary light radiated from the
LED chip 10 can be emitted solely or primarily from the upper
surface 11 thereof so as to penetrate the photoluminescent
structure 20. One of the vertical side surfaces 231b or 231d of the
photoluminescent structure 20 is covered by the reflective
structure 30 to form a side reflective surface, for example the
vertical side surface 231b as illustrated in FIG. 2C in this
embodiment. The vertical side surfaces 231a and 231c and the top
surface 21 are not covered by the reflective structure 30. That is,
they are exposed outside the reflective structure 30, wherein the
vertical side surfaces 231a, 231c, and 231d that are not covered by
the reflective structure 30 form three side light-emitting
surfaces, and the top surface 21 that is not covered by the
reflective structure 30 forms a top light-emitting surface.
[0066] Thus, after the light beam L is emitted from the upper
surface 11 of the LED chip 10 to enter the photoluminescent
structure 20, partial light beam L that travels toward the vertical
side surface 231b will be reflected (or absorbed) by the reflective
structure 30 so as to be mixed with another portion of the light
beam L, which will be emitted out of the photoluminescent structure
20 from the vertical side surfaces 231a, 231c, and 231d and the top
surface 21. Therefore, the viewing angle of the light beam L is
less affected by the reflective structure 30 along the first
horizontal direction D1. Along the second horizontal direction D2,
because the vertical side surface 231b is shielded by the
reflective structure 30, the viewing angle is constrained and
radiation is biased toward the vertical side surface 231d that is
not covered by the reflective structure 30. That is, with respect
to the normal direction of the upper surface 11 of the LED chip 10
(for example, the optical axis of the upper surface 11) and along
with the second horizontal direction D2, the radiation pattern is
asymmetrical.
[0067] Therefore, the LED 2A may also provide different viewing
angles in different horizontal directions D1 and D2 so as to
achieve the purpose of providing an asymmetrical radiation pattern.
The LED 2A also has an asymmetrical radiation pattern with respect
to the optical axis of the upper surface 11 of the LED chip 10
along the second horizontal direction D2.
[0068] As illustrated in FIGS. 3A to 3D, two perspective views and
two cross-sectional views of an LED 3A are shown according to
another embodiment of the present disclosure, wherein, for the
purpose of illustration, a photoluminescent structure 20 is used as
an example to illustrate the optical structure 20. The LED 3A is
different from the light-emitting device 2A at least in that the
upper surface 11 of the LED chip 10 of the LED 3A and the four
vertical edge surfaces 131a to 131d of the edge surface 13 are
covered by the photoluminescent structure 20. The top surface 21 of
the photoluminescent structure 20 is substantially completely
covered (e.g., covers at least 90%, at least 95%, at least 98%, or
at least 99% or more of a total surface area) by a reflective
structure 30 to form an upper reflective surface, and its side
surface 23 is partially covered by the reflective structure 30.
[0069] More specifically, one of the vertical side surfaces 231b or
231d of the photoluminescent structure 20 (for example, the
vertical side surface 231d illustrated in FIG. 3C) and the top
surface 21 are simultaneously covered by the reflective structure
30 to form a side reflective surface and an upper reflective
surface, respectively. Since the vertical side surfaces 231a to
231c are not covered by the reflective structure 30 and thus are
exposed outside the reflective structure 30, the LED 3A has three
side light-emitting surfaces.
[0070] In this way, after the primary light is emitted from the LED
chip 10 and enters the photoluminescent structure 20, a portion of
the light traveling toward the vertical side surface 231d or the
top surface 21 will be reflected (or absorbed) by the reflective
structure 30, and will be mixed together with another portion of
light to form the light beam L and exit the photoluminescent
structure 20 from either one of the vertical side surfaces 231a,
231b or 231c. Therefore, the viewing angle is constrained along the
second horizontal direction D2 of the LED 3A. Compared with the
LEDs 1A and 2A wherein light emits mainly from the top surface and
some from the vertical side surfaces, the light beam L emitted from
the light-emitting device 3A is mainly from the vertical side
surface 231b and some from the vertical side surfaces 231a and 231c
so that a large amount of laterally transmitted light can be
emitted to form a side-view LED.
[0071] Since most of the light is transmitted from the vertical
side surface 231b of the photoluminescent structure 20, the
vertical side surface 231b is the primary light-emitting surface of
the LED 3A. Because the primary light-emitting surface and the
lower electrode surface of the LED chip 10 are substantially
perpendicular to each other, the LED 3A is a side-view CSP LED. For
ease of description, a length direction S1 and a width direction S2
perpendicular to each other are specified along the vertical side
surface 231b (the primary light-emitting surface), and both the
length direction S1 and the width direction S2 are substantially
perpendicular to the second horizontal direction D2. Through the
arrangement of the reflective structure 30 according to this
embodiment, the light beam L can be solely or primarily emitted
from the vertical side surfaces 231a, 231b and 231c (three side
light-emitting surfaces). Therefore the LED 3A can have a larger
viewing angle along the length direction S1. On the other hand, due
to the fact that the top surface 21 of the photoluminescent
structure 20 is covered by the reflective structure 30, the LED 3A
has a smaller viewing angle along the width direction S2.
Accordingly, the LED 3A can provide different viewing angles along
the length direction S1 and along the width direction S2.
Furthermore, the primary light-emitting surface of the LED 3A is
perpendicular to the lower electrode surface of the LED chip 10,
which is different from the orientation of the primary
light-emitting surface of the LEDs 1A and 2A. Therefore, besides
providing asymmetrical lighting applications, the LED 3A is a
side-view LED.
[0072] FIG. 3E and FIG. 3F are two schematic cross-sectional views
of an LED 3B according to another embodiment of the present
disclosure, wherein, for the purpose of illustration, a
photoluminescent structure 20 is used as an example embodiment of
the optical structure 20. The LED 3B is different from the LED 3A
at least in that the photoluminescent structure 20 of the
light-emitting device 3B covers the edge surface 13 of the LED chip
10 (and does not cover the upper surface 11), and the reflective
structure 30 covers both the upper surface 11 of the LED chip 10
and the top surface 21 of the photoluminescent structure 20.
[0073] Specifically, the photoluminescent structure 20 of the LED
3B covers the edge surface 13 of the LED chip 10, and desirably,
the top surface 21 of the photoluminescent structure 20 is
substantially flush or coplanar with the upper surface 11 of the
LED chip 10. The reflective structure 30 is disposed to form an
upper reflective surface to cover the upper surface 11 and the top
surface 21 simultaneously. In addition, one of the vertical side
surfaces 231b or 231d of the photoluminescent structure 20 (for
example the vertical side surface 231d as illustrated in FIG. 3E)
is covered by the reflective structure 30 to form a side reflective
surface, so that the vertical side surfaces 231a, 231b, and 231c
are not covered by the reflective structure 30. Therefore, these
surfaces are exposed from the reflective structure 30 to form three
side light-emitting surfaces.
[0074] Thus, a primary light solely or primarily escapes from the
edge surface 13 of the LED chip 10 and enters the photoluminescent
structure 20, wherein part of the light traveling toward the
vertical side surface 231d will be reflected (or absorbed) by the
reflective structure 30, and will be mixed together with another
portion of the light beam L to exit the photoluminescent structure
20 from any of the vertical side surfaces 231a, 231b or 231c.
Compared with the LED 3A, during the transmission of the light,
multiple reflections could occur between the upper surface 11 of
the LED chip 10 and the top surface 21 of the photoluminescent
structure 20 to cause loss of light energy. Therefore, when the
reflective structure 30 is formed directly covering the upper
surface 11 of the LED chip 10, the light extraction efficiency of
the LED 3B can be further improved by avoiding the energy loss
caused by multiple reflections.
[0075] It should be noted that, in order to prevent unnecessary
light energy from being dissipated due to multiple reflections, the
width of the LED chip 10 of the LEDs 3A and 3B along the second
horizontal direction D2 is desirably smaller than the length of the
LED chip 10 along the first horizontal direction D1. When the
dimension is smaller along the second horizontal direction D2 in
the embodiment, the light traveling toward the vertical side
surface 231d and being reflected back by the reflective structure
30 can experience a shorter optical path. Together with other
radiated light, the light beam L is emitted from any of the
vertical side surfaces 231a, 231b and 231c of the photoluminescent
structure 20.
[0076] Next, as illustrated in FIGS. 4A to 4D, two perspective
views and two cross-sectional views of an LED 4A are shown,
according to another embodiment of the present disclosure, wherein,
for the purpose of illustration, a photoluminescent structure 20 is
used as an example embodiment of the optical structure 20. The LED
4A is different from the LED 3A at least in that the upper surface
11 of the LED chip 10 of the LED 4A and the four vertical edge
surfaces 131a to 131d of the edge surface 13 are covered by the
photoluminescent structure 20, and the top surface 21 and three
vertical side surfaces of the side surface 23 of the
photoluminescent structure 20 are all covered by the reflective
structure 30.
[0077] Specifically, one of the vertical side surfaces 231b or 231d
of the photoluminescent structure 20 (for example the vertical side
surface 231d as illustrated in FIG. 4C), the vertical side surfaces
231a and 231c, and the top surface 21 are simultaneously covered by
the reflective structure 30 to form three side reflective surfaces
and an upper reflective surface, respectively. The vertical side
surface 231b is not covered by the reflective structure 30, and
thus is exposed from the reflective structure 30 to form a side
light-emitting surface.
[0078] Specifically, after the primary light is emitted from the
LED chip 10 and enters the photoluminescent structure 20, part of
the light traveling toward the vertical side surfaces 231a, 231c,
231d and the top surface 21 will be reflected (or absorbed) by the
reflective structure 30, and the light will be mixed along with
other radiated light and will be emitted from the vertical side
surface 231b out of the photoluminescent structure 20. Thus, the
orientation of the primary light-emitting surface of the LED 4A is
substantially perpendicular to the lower electrode surface of the
LED chip 10, which is also different from the orientation of the
primary light-emitting surface of the LEDs 1A and 2A.
[0079] Therefore, it can also be used as a side-view LED.
[0080] As illustrated in FIG. 4E and FIG. 4F, two schematic
cross-sectional views of an LED 4B are shown according to another
embodiment of the present disclosure, wherein, for the purpose of
illustration, a photoluminescent structure 20 is used as an example
embodiment of the optical structure 20. The LED 4B is different
from the LED 4A at least in that the photoluminescent structure 20
of the LED 4B covers the edge surface 13 of the LED chip 10 (and
does not cover the upper surface 11), and the reflective structure
30 simultaneously covers the upper surface 11 of the LED chip 10
and the top surface 21 of the photoluminescent structure 20 as well
as the three vertical side surfaces 231a, 231c, and 231d of the
photoluminescent structure 20.
[0081] Specifically, the photoluminescent structure 20 covers the
edge surface 13 of the LED chip 10. Desirably, the top surface 21
of the photoluminescent structure 20 is substantially flush or
coplanar with the upper surface 11 of the LED chip 10, and both the
top surface 21 and the upper surface 11 are simultaneously covered
by the reflective structure 30 to form an upper reflective surface.
In addition, one of the vertical side surfaces 231b or 231d of the
photoluminescent structure 20 (for example the vertical side
surface 231d as illustrated in FIG. 4E) and the vertical side
surfaces 231a and 231c and the top surface 21 are simultaneously
covered by the reflective structure 30, wherein the vertical side
surfaces 231a, 231c, and 231d are covered by the reflective
structure 30 to form three side reflective surfaces, while the
vertical side surface 231b is not covered by the reflective
structure 30 and thus is exposed outside the reflective structure
30 to form a side light-emitting surface.
[0082] Therefore, the primary light solely or primarily exits from
the edge surface 13 of the LED chip 10 and enters the
photoluminescent structure 20, and part of the light traveling
toward the three vertical side surfaces 231a, 231c, 231d or the top
surface 21 will be reflected (or absorbed) by the reflective
structure 30, and escape out the photoluminescent structure 20 from
the vertical side surface 231b together with another portion of the
light beam L. Similar to the advantages of the LED 3B, the
reflective structure 30 directly covers the upper surface 11 of the
LED chip 10 so that the light extraction efficiency of the LED 4B
can be further improved by avoiding the energy loss caused by
multiple reflections.
[0083] It should be noted that in order to prevent unnecessary
light energy from being reflected due to multiple reflections, the
width of the LED chip 10 of the LEDs 4A and 4B along the second
horizontal direction D2 is preferably to be smaller than the length
along the first horizontal direction D1 so that the light traveling
toward the vertical side surfaces 231a, 231c, 231d or the top
surface 21 and reflected by the reflective structure 30 will
experience a shorter optical path before being mixed together with
other light beam L and emitted from the vertical side surface 231b
of the photoluminescent structure 20.
[0084] In summary, the LEDs 1A, 2A, 3A, 3B, 4A, and 4B can provide
the following common advantages. All of them have a small-size form
factor because they are all CSP LEDs. Desirably the length (or
width) of the LED 1A, 2A, 3A, 3B, 4A, or 4B is not more than about
2.0 times, about 1.6 times or about 1.2 times the length (or width)
of the LED chip 10. Therefore, it is suitable to be assembled and
embedded inside other electronic devices.
[0085] Furthermore, since an asymmetrical radiation pattern can be
generated without incorporating a primary optical lens or a
secondary optical lens, the cost of the overall optical system can
be reduced, and the space for an optical lens can be saved.
[0086] In addition, the asymmetrical optical radiation pattern of
the LED according to embodiments of the present disclosure can make
the final product have other design advantages. For example, it can
replace the side-view PLCC-type LED as a light source of the
edge-lit type backlight module for LCD televisions and mobile
devices, and the asymmetrical radiation pattern can provide a
larger viewing angle along the length direction of the backlight
module, so the area of a dark area or spot can be reduced or the
spacing distance between two adjacent LEDs can be increased to
reduce the number of LEDs used in a light bar. Simultaneously,
along the thickness direction of the backlight module, the
asymmetrically shaped LED provides a smaller viewing angle, so that
the light emitted by the LED can be efficiently transmitted to the
light guide plate of the backlight module to reduce the loss of
light energy.
[0087] In addition, the primary light-emitting surface and the
lower electrode surface of the LED according to some embodiments of
the present disclosure may be substantially perpendicular to each
other to form a side-view CSP LED. When applied to an edge-lit
backlight module, the LED may allow the application mounting board
of the backlight module to omit a vertical surface (refer to the
technical content of the backlight module 600 in FIG. 6 to be
described below), thereby minimizing the overall thickness of the
backlight module along the normal direction of the light-emitting
surface, and reducing the difficulty in designing and
manufacturing. In this way, a display using this backlight module
can achieve a narrower bezel frame.
[0088] In addition, the light emitted by the LEDs 1A, 2A, 3A, 3B,
4A, and 4B may also be specified to be more asymmetrically shaped
through incorporating additional secondary optical lenses for some
applications that specify a more asymmetrically shaped radiation
pattern.
[0089] In addition, it will be appreciated that the technical
features disclosed in the foregoing LED 1A, for example a
substantially transparent light-transmitting structure 20 as an
embodiment of the optical structure 20, can also be applied to the
LEDs 2A, 3A, 3B, 4A, and 4B to form a monochromatic light CSP LED
having an asymmetrical radiation pattern. Other technical features
disclosed according to the LED 1A, such as including a
micro-structured lens layer or a submount substrate, can also be
applied to the LEDs 2A, 3A, 3B, 4A, and 4B.
[0090] Next, a backlight module including any one of the LEDs
described above will be described. FIGS. 5 and 6 respectively
illustrate a backlight module with various aspects of
configuration, wherein the former includes a plurality of LEDs 1A
or a plurality of LEDs 2A that can emit light from the top surface
21, and the latter includes a plurality of LEDs 3A, 3B, 4A or 4B
that emit light from a side light-emitting surface. The backlight
modules further include an application mounting board, any one of
the aforementioned LEDs (which may include a photoluminescent
structure if white light is specified, or a light-transmitting
structure if monochromatic light is specified), a reflective layer,
and a light guide plate. The technical features of the components
will be described in sequence as follows.
[0091] The backlight module 500 shown in FIG. 5 includes an
application mounting board 510, an LED capable of emitting light
from the top surface 21 (for example, the LED 1A), a reflective
layer 520, and a light guide plate 530. The application mounting
board 510 includes a horizontal portion 511 having a horizontal
surface, a vertical portion 512 having a vertical surface, and a
reflective layer 513. The horizontal portion 511 and the vertical
portion 512 are substantially perpendicular to each other, and the
reflective layer 513 covers at least the horizontal surface of the
horizontal portion 511, or the vertical surface of the vertical
portion 512 or both. For example, as illustrated in FIG. 5, both of
the horizontal surface of the horizontal portion 511 and the
vertical surface of the vertical portion 512 are covered by the
reflective layer 513. The reflective layer 513 may be, for example,
a metal thin film, a metal plate, or a high-reflectivity white
paint. In addition, the application mounting board 510 may also be
a flexible application mounting board.
[0092] As illustrated in FIG. 5, the LED 1A is disposed on the
vertical surface of the vertical portion 512 of the application
mounting board 510. The set of electrodes 14 of the LED chip 10 is
electrically connected with the application mounting board 510. The
LED 1A is disposed in such a configuration that, along the second
horizontal direction D2, the vertical side surface 231d that is not
covered by the reflective structure 30 faces the horizontal surface
of the horizontal portion 511 of the application mounting board
510, and the vertical side surface 231b that is covered by the
reflective structure 30 faces away from the horizontal portion
511.
[0093] The reflective layer 520 is disposed above the horizontal
portion 511 of the application mounting board 510 (and may be
disposed above the reflective layer 513) and extends away from the
vertical portion 512 and away from the LED 1A. The reflective layer
520 may be, for example, a metal thin film, a metal plate or other
structures. The light guide plate 530 is disposed on the reflective
layer 520 and includes an incident-light side surface 531 and an
exiting-light surface 532 substantially perpendicular to each
other. The exiting-light surface 532 is connected to the
incident-light side surface 531, and the exiting-light surface 532
is configured to be substantially parallel to but away from the
reflective layer 520 (facing away from the reflective layer
520).
[0094] Accordingly, the top surface 21 of the LED 1A faces the
incident-light side surface 531 of the light guide plate 530.
Desirably, the length of the LED 1A along the second horizontal
direction D2 is not greater than the thickness of the light guide
plate 530 measured along a normal direction of the exiting-light
surface 532. In other words, the dimension of the light-emitting
surface of the LED 1A is desirably smaller than the dimension of
the incident-light side surface 531. Therefore, the light emitted
from the top surface 21 of the LED 1A can be effectively
transmitted to the incident-light side surface 531 of the light
guide plate 530. Because the vertical side surface 231d of the LED
1A is not covered by the reflective structure 30, light escaping
from the vertical side surface 231d is largely emitted toward the
reflective layer 513. Since the reflective layer 513 is readily
fabricated using a high-reflectivity material, the reflectivity of
the reflective layer 513 can be made higher than the reflectivity
of the reflective structure 30. Therefore, after being reflected by
the reflective layer 513, the light emitted toward the reflective
layer 513 (for example the light beam L1 as illustrated in FIG. 5)
can be guided to the incident-light side surface 531 more
effectively. In this way, the loss of light energy can be reduced,
so that the backlight module 500 can have higher efficiency of
light energy utilization. The reflective layer 520 disposed
underneath the light guide plate 530 can reflect light so that most
of the light is transmitted out from the exiting-light surface
532.
[0095] As illustrated in FIG. 6, the backlight module 600 includes
an application mounting board 610, a plurality of side-emitting
LEDs (for example the LED 3A), a reflective layer 620, and a light
guide plate 630. The application mounting board 610 includes a
horizontal portion 611 including a horizontal surface, and a
reflective layer 613 disposed above and covering the horizontal
surface of the horizontal portion 611.
[0096] The LED 3A is disposed on the horizontal portion 611 of the
application mounting board 610, and the set of electrodes 14 of the
LED chip 10 is electrically connected with the application mounting
board 610. The reflective layer 620 is also disposed above the
horizontal portion 611 of the application mounting board 610 and
extends away from the LED 3A. The light guide plate 630 is disposed
above the reflective layer 620 and includes an incident-light side
surface 631 and an exiting-light surface 632 substantially
perpendicular to each other. The exiting-light surface 632 is
connected to the incident-light side surface 631, and the
exiting-light surface 632 is configured to be substantially
parallel to but facing away from the reflective layer 620.
[0097] As illustrated in FIG. 6, the vertical side surface 231b of
the LED 3A substantially perpendicular to the second horizontal
direction D2 is not covered by the reflective structure 30 and is
facing toward the incident-light side surface 631 of the light
guide plate 630. On the other hand, the vertical side surface 231d
is covered by the reflective structure 30 and is facing away from
the incident-light side surface 631. In addition, a length of the
LED 3A along a normal direction of the upper surface 11 of the LED
chip 10 is desirably not greater than a thicknesses of the light
guide plate 630 along a normal direction of the exiting-light
surface 632.
[0098] In this way, under the guidance of the reflective structure
30 and the reflective layer 613, the LED 3A can emit light from the
three vertical side surfaces 231a, 231b and 231c and can
effectively be transmitted to the incident-light side surface 631
of the light guide plate 630. The reflective layer 620 under the
light guide plate 630 can reflect light so that most of the light
is transmitted out of the light guide plate 630 from the
exiting-light surface 632. Compared with the backlight module 500,
the application mounting board 610 of the backlight module 600
includes the horizontal portion 611 and does not include another
vertical portion. Therefore, along the direction of its
light-emitting surface (D2 direction shown in FIG. 6) of the light
bar module (including the application mounting board 610 and the
LEDs 3A), a space is included for accommodating the LED 3A without
accommodating the application mounting board 610. Thus the light
bar module can have a smaller dimension along the D2 direction,
which is advantageous for the design and manufacture of an LCD
panel with a narrower bezel frame.
[0099] As illustrated in FIGS. 7A and 7B, a side view and a top
view of a backlight module 600 are shown, respectively, including a
plurality of LEDs 3A and 4A. Since the LED 3A can emit light from
the three vertical side surfaces 231a, 231b and 231c, the viewing
angle along the first horizontal direction D1 illustrated in FIG.
7A will be greater than the viewing angle of the LED 4A along the
first horizontal direction D1 illustrated in FIG. 7B, thereby
effectively reducing the dark area of the light guide plate 630
which may be caused in an area between adjacent LEDs 3A. Also, the
distance between adjacent LEDs 3A may also be increased to reduce
the number of LEDs 3A used in the backlight module 600, thereby
reducing the overall module cost. In contrast, the LED 4A may have
a technical feature that the radiated light is more concentrated
toward the forward direction that is perpendicular to the first
horizontal direction D1.
[0100] Next, a method for manufacturing an LED according to an
embodiment of the present disclosure will be described. The method
may include at least two process stages: firstly, providing a
photoluminescent structure 20 (it may also be replaced by a
light-transmitting structure, which will not be described in detail
below) to cover an upper surface 11 and/or an edge surface 13 of an
LED chip 10; and secondly, forming a reflective structure 30 to
partially cover a side surface 23 of the photoluminescent structure
20 (or light-transmitting structure). Hereinafter, the LEDs 1A to
4B will be sequentially described as an example to further describe
the technical details of the manufacturing method, which may be
referred to the technical features of the embodiments of the LEDs
1A to 4B.
[0101] As illustrated from FIG. 8A to FIG. 12B, schematic diagrams
of the process stages of the method to fabricate the LED 1A
according to an embodiment of the present disclosure.
[0102] As shown in FIG. 8A, a plurality of LED chips 10 are first
arranged with a specified pitch on a release material 80 to form an
array of LED chips 10. Desirably, the LED chip 10 can be pressed
against the release material 80 so that the set of electrodes 14 is
embedded in the release material 80 without being exposed. In
addition, the release material 80 may be a release film, an
ultraviolet (UV) release tape, a thermal release tape, or the like.
As shown in FIG. 8B, the photoluminescent structure 20 is disposed
on the LED chips 10 and substantially completely covers the upper
surface 11 and the edge surface 13 of each LED chip 10.
[0103] As illustrated from FIG. 9A to FIG. 9C, a portion of the
photoluminescent structure 20 is then cut and removed along the
first horizontal direction D1 to form a first trench 90, wherein
the first trench 90 is cut along one vertical edge surface of the
edge surface 13 of the LED chip 10 (such as the vertical edge
surface 131b). After the first trench 90 is formed, the vertical
side surface 231b is exposed and will be subsequently covered by a
reflective structure 30.
[0104] After the cutting is completed, as shown in FIGS. 10A and
10B, the reflective structure 30 is formed inside to fill the gap
of the first trench 90 by molding or dispensing, wherein the
reflective structure 30 substantially completely covers the
vertical side surface 231b of the photoluminescent structure 20,
and the top surface 31 of the reflective structure 30 may be
substantially flush with the top surface 21 of the photoluminescent
structure 20 so that the top surface 21 of the photoluminescent
structure 20 is exposed from the reflective structure 30.
[0105] If a molding method is used to form the reflective structure
30, the photoluminescent structure 20, the LED chip 10 and the
release material 80 are placed in a mold (not shown), and then the
manufacturing material of the reflective structure 30 is injected
into the mold so that the vertical side surface 231b of the
photoluminescent structure 20 is covered. When the manufacturing
material is cured and solidified, the reflective structure 30 can
be formed. If a dispensing method is used to form the reflective
structure 30, the above-mentioned mold may be omitted. Instead, the
manufacturing material of the reflective structure 30 is directly
dispensed onto the release material 80, and then the manufacturing
material is gradually increased on the release material 80 to cover
the vertical side surface 231b of the photoluminescent structure
20. In this case, the top surface 31 of the reflective structure 30
may also be designed to be slightly lower than the top surface 21
of the photoluminescent structure 20, so as to prevent the
manufacturing material of the reflective structure 30 from
spreading to the top surface 21 of the photoluminescent structure
20.
[0106] After the reflective structure 30 is formed, as shown in
FIGS. 11A and 11B, the release material 80 may be removed to obtain
an array of connected LEDs 1A. The reflective structures 30 of the
LEDs 1A may be connected, so that a singulation process stage (as
shown in FIGS. 12A and 12B) may be taken to cut the connected
photoluminescent structures 20 and the reflective structure 30
along the second horizontal direction D2 to form the vertical side
surfaces 231a and 231c that are not covered by the reflective
structure 30. Similarly, another singulation procedure is performed
to cut the connected photoluminescent structures 20 and the
reflective structures 30 along the first horizontal direction D1 to
form the vertical side surfaces 231d and the vertical side surface
231b, which are shielded by the reflective structure 30. In this
way, a plurality of LEDs 1A that are separated from each other can
be obtained, wherein the one vertical side surface 231b is shielded
by the reflective structure 30.
[0107] The above is a description of the method of manufacturing
the LED 1A. Next, the method of manufacturing the LED 2A will be
described. Since the method of manufacturing the LED 2A is
partially the same as or similar to the method of manufacturing the
LED 1A, detailed description of similar process stages will be
appropriately omitted.
[0108] FIGS. 13A to 17B are schematic diagrams of process stages of
a manufacturing method to fabricate the LED 2A.
[0109] As shown in FIG. 13A, a release material 80 is first
provided, and a photoluminescent structure 20 is formed on the
release material 80 through a manufacturing process such as spray
coating, printing, or molding. Alternatively, the photoluminescent
structure 20 is completed first, and then the photoluminescent
structure 20 is attached and placed on the release material 80 with
the top surface 21 of photoluminescent structure 20 facing toward
the release material 80.
[0110] Next, as shown in FIG. 13B, a plurality of LED chips 10 are
placed upside down on the photoluminescent structure 20 so that the
upper surface 11 of the LED chip 10 faces downwards and is placed
on the photoluminescent structure 20. At this time, the set of
electrodes 14 of each LED chip 10 faces upwards and is exposed from
the release material 80.
[0111] Then, as shown in FIGS. 14A to 14C, the photoluminescent
structure 20 is cut along the first horizontal direction D1 so that
a portion of the photoluminescent structure 20 is removed to form a
first trench 90', which will be formed close to one specific edge
portion of the LED chip 10 (for example, the vertical edge surface
131b). After the removal process of the first trench is completed,
as shown in FIG. 14B, the photoluminescent structures 20 along the
first horizontal direction D1 are still connected. Along the second
horizontal direction D2, as shown in FIG. 14C, the photoluminescent
structures 20 are separated by the first trenches 90' to expose the
vertical side surface 231b, which will be covered by a reflective
structure 30.
[0112] Next, as shown in FIGS. 15A and 15B, the reflective
structure 30 is formed between the first trenches 90' to fill the
gap of the first trenches 90' and the edge surface 13 of each LED
chip 10, and substantially completely covers the edge surface 13 of
the LED chip 10 and the vertical side surface 231b of the
photoluminescent structure 20.
[0113] After the reflective structure 30 is formed, the release
material 80 is removed (as shown in FIGS. 16A and 16B) to obtain a
plurality of LEDs 2A. The photoluminescent structures 20 and the
reflective structures 30 of the LEDs 2A may be connected, so a
singulation process (as shown in FIGS. 17A and 17B) may be
performed to disconnect the connected photoluminescent structures
20 and the reflective structures 30 so that the LEDs 2A separated
from each other are obtained. Specifically, as shown in FIG. 17A,
the connected photoluminescent structure 20 and the reflective
structure 30 are cut along the second horizontal direction D2 to
form the vertical side surfaces 231a and 231c that are exposed from
the reflective structure 30. Similarly, as shown in FIG. 17B, the
connected photoluminescent structures 20 and the reflective
structures 30 are cut along the first horizontal direction D1 so
that the vertical side surface 231b is still shielded by the
reflective structure 30, whereas the vertical side surface 231d is
exposed from the reflective structure 30.
[0114] The above is a description of the manufacturing method to
fabricate the LED 2A. Next, a method of fabricating the LEDs 3A and
3B will be described. Detailed description of the same or similar
fabrication stages as those of the manufacturing methods to
fabricate the LEDs 1A and 2A will be appropriately omitted.
[0115] As shown in FIG. 18A, a plurality of LED chips 10 are first
arranged with a specified pitch on a release material 80.
Desirably, as illustrated in FIG. 19A, the width of the LED chips
10 along the second horizontal direction D2 is smaller than the
length of the LED chips 10 along the first horizontal direction D1.
Next, as shown in FIG. 18B, photoluminescent structures 20 are
formed on the LED chips 10 and substantially completely cover the
upper surface 11 and the edge surface 13 of each LED chip 10.
However, in this specific embodiment, the thickness of the
photoluminescent structure 20 covered on the upper surface 11 of
the LED chips 10 may be smaller than that corresponding to the LED
3A.
[0116] Referring to FIGS. 19A to 19C, the photoluminescent
structure 20 is then cut along the first horizontal direction D1 to
form a first trench 90. When cutting, the first trench 90 will be
formed uniformly toward one specific edge surface (for example, a
vertical edge surface 131d as illustrated in FIGS. 19A and 19C) of
the chip 10 so as to expose the vertical side surface 231d of the
photoluminescent structure 20, which will be covered by a
reflective structure 30 in the next fabrication stage.
[0117] After the trench removal is completed, as shown in FIG. 20A
and FIG. 20B, the reflective structure 30 is formed to fill the gap
of the first trench 90. In contrast to fabricating the LED 1A, the
reflective structure 30 substantially completely covers the
vertical side surface 231d as well as the top surface 21 of the
photoluminescent structure 20.
[0118] After the reflective structure 30 is formed, as shown in
FIGS. 21A and 21B, the release material 80 can be removed to obtain
a plurality of LEDs 3A. Then, as shown in FIGS. 22A and 22B, a
singulation process can be performed to separate the connected
photoluminescent structures 20 and the reflective structures 30
along the second horizontal direction D2 to expose the vertical
side surfaces 231a and 231c, which are not covered by the
reflective structure 30. Then another dicing process can be
performed to separate the connected photoluminescent structures 20
and the reflective structures 30 along the first horizontal
direction D1 to form the vertical side surface 231b. The vertical
side surface 231d is still shielded by the reflective structure 30.
In this way, a plurality of mutually separated LEDs 3A can be
obtained.
[0119] The above manufacturing method may be performed to fabricate
the LED 3B after slight modification. That is, referring to FIG.
18B in the fabrication stage to form the photoluminescent structure
20, the photoluminescent structure 20 is formed selectively between
the edge surfaces 13 of the LED chips 10, but does not cover the
upper surface 11 of the LED chip 10. Alternatively, the
photoluminescent structure 20 may be formed to cover the upper
surface 11 of the LED chip 10, and then the portion covering the
upper surface 11 may be removed.
[0120] The above is a description of the method of fabricating the
LEDs 3A and 3B. Next, a method of fabricating the LEDs 4A and 4B
will be described. Detailed description of the same or similar
fabrication processes as those of the LEDs 3A and 3B will be
appropriately omitted.
[0121] As shown in FIG. 18A, first, a plurality of LED chips 10 are
arranged with a specified pitch on a release material 80, and then,
as shown in FIG. 18B, the photoluminescent structures 20 are
disposed on the LED chips 10. Thereafter, as shown in FIGS. 19A to
19C, the photoluminescent structure 20 is cut along the first
horizontal
[0122] direction D1 to form a first trench 90 to expose the
vertical side surface 231d, which will be covered by a reflective
structure 30.
[0123] As illustrated from FIG. 23A to FIG. 23C, the fabrication
process is different from the method to fabricate the LED 3A. After
the first trench 90 is formed, another cutting process stage will
be performed. That is, the photoluminescent structure 20 is cut
along the second horizontal direction D2 to form a second trench
91, and to expose the two vertical side surfaces 231a and 231c
disposed opposite to each other substantially perpendicular to the
first horizontal direction D1.
[0124] After the two trench removal processes are completed,
reflective structures 30 (not shown) are formed inside the first
and second trenches 90 and 91 to cover the vertical side surfaces
231a, 231c, and 231d of the photoluminescent structure 20, and to
fill the gap of the first and second trenches 90 and 91.
Furthermore, the reflective structure 30 substantially completely
covers the top surface 21 of the photoluminescent structure 20.
After the reflective structure 30 is formed, the release material
80 can be removed to obtain a plurality of LEDs 4A or 4B. Then, a
singulation process can be performed to obtain the plurality of
LEDs 4A or 4B separated from each other.
[0125] In summary, the method for manufacturing an LED according to
embodiments of the present disclosure can produce various LEDs that
can effectively control the radiation pattern and the viewing angle
along at least one specific horizontal direction, or form a CSP LED
with a side-view light-emitting structure. Such LEDs can be
manufactured in a batch manner.
[0126] While the disclosure has been described with reference to
the specific embodiments thereof, it should be understood by those
skilled in the art that various changes may be made and equivalents
may be substituted without departing from the true spirit and scope
of the disclosure as defined by the appended claims. In addition,
many modifications may be made to adapt a particular situation,
material, composition of matter, method, or process to the
objective, spirit and scope of the disclosure. All such
modifications are intended to be within the scope of the claims
appended hereto. In particular, while the methods disclosed herein
have been described with reference to particular operations
performed in a particular order, it will be understood that these
operations may be combined, sub-divided, or re-ordered to form an
equivalent method without departing from the teachings of the
disclosure. Accordingly, unless specifically indicated herein, the
order and grouping of the operations are not limitations of the
disclosure.
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